 The entire army then marched past Graus, which had resisted assault twice before, and moved against Barbastro, then part of the taifa of Lleida ruled by Al-Muzaffar.The city was besieged for forty days until it surrendered according to both Muslim and Christian sources.Aside from William of Montreuil and Guy-Geoffrey, a 1078 story about the Normans placed Robert Crispin as the leader of the campaign.